1. Field of the Invention
The present invention relates to a self-winding watch structured to wind up a spiral spring in a barrel complete due to rotation of an oscillating weight and, more particularly, to a self-winding watch having a self-winding mechanism constituted by components including a pawl lever arranged on a main plate side of a bridge member thereof.
2. Background Information
Referring to FIG. 5, in a conventional self-winding watch a movement 500 of the self-winding watch is provided with a main plate 102, a train wheel bridge 104 and a center wheel bridge 106.
The xe2x80x9cmovementxe2x80x9d herein refers to a watch mechanical part, and a xe2x80x9cglass sidexe2x80x9d signifies a side on which a glass 110 is present when a movement is assembled in a case. Meanwhile, a xe2x80x9cback lid sidexe2x80x9d shows a side where a back lid 112 exists when a movement is assembled in a case. Accordingly, the train wheel bridge 104 and the center wheel bridge 106 are assembled on a back lid side of the main plate 102.
A date indicator maintaining plate 116 is assembled on a glass side of the main plate 102. A dial 118 is assembled on a glass side of the date indicator maintaining plate 116.
A barrel complete 120, a minute wheel 122, a second wheel 124 and a hour wheel 126 are rotatably assembled in the movement 500. A glass 110 protects the movement 500.
A ratchet wheel 150 is assembled on a back lid side of the train wheel bridge 104. The ratchet wheel 150 has a square hole 150a assembled on a corner part 120b of a barrel complete stem 120a of a barrel complete 120. A ratchet wheel screw 152 fixes the ratchet wheel 150 on the barrel complete stem 120a. 
An-oscillating weight 160 includes a ball bearing part 162, an oscillating weight body 164 and a weight 166. The ball bearing part 162 includes an inner ring 168, a ball stopper ring 170 and an outer ring 172 to assemble a plurality of balls 174 in between the inner ring 168, the ball stopper ring 170 and the outer ring 172. An oscillation weight pinion 176 is provided on an outer periphery of the outer ring 172.
A first transmission wheel 180 is rotatably assembled on the train wheel bridge 104 and main plate 102. The first transmission wheel 180 has a first transmission gear 180a, an upper guide shaft part 180b and a lower guide shaft part 180c. The first transmission gear 180a is structured to mesh with the oscillating weight pinion 176 through a first transmission intermediate wheel 178. An eccentric shaft part 180d is provided between the first transmission gear 180a and the upper guide shaft part 180b on the first transmission wheel 180. The upper guide shaft part 180b is rotatably supported on the train wheel bridge 104. The lower guide shaft part 180c is rotatably supported on the main plate 102.
A pawl lever 182 is assembled in between the first transmission gear 180a and the train wheel bridge 104. Consequently, the pawl lever 182 is arranged on a back lid side of the train wheel bridge 104 as a bridge member. The pawl lever 182 has a push pawl (not shown) and a draw pawl 182c. The pawl lever 182 at its guide hole 182a is rotatably assembled over the eccentric shaft part 180d of the first transmission wheel 180. A transmission holder 183 is attached to the first transmission wheel 180 in a closer position than the eccentric shaft part 180d to the lower guide shaft part 180c. 
A second reduction wheel 184 is assembled on a back lid side of the train wheel bridge 104 and rotatably attached by a second reduction screw 185. The second reduction wheel 184 has a second reduction gear 184a and a second reduction pinion 184b. The second reduction gear 184a is structured in a ratchet gear form. The push pawl and draw pawl 182c of the pawl lever 182 engage this ratchet gear 184a. The second reduction pinion 184b is in mesh with the ratchet wheel 150.
When the oscillating weight 160 rotates, the rotation of oscillating weight pinion 176 causes rotation in the first transmission wheel 180. The pawl lever 182 is reciprocally moved based on eccentric motion of the eccentric shaft part 180d by the rotation of first transmission wheel 180, causing the second reduction wheel 184 to rotate in a given direction through the push pawl and draw pawl 182c. The rotation of second reduction wheel 184 rotates the ratchet wheel 150, thus winding up the spiral spring 120c in the barrel complete 120.
However, the conventional self-winding watch using a pawl lever has the following problems.
(1) Because the pawl lever is arranged between the bridge member supporting oscillating weight and the oscillating weight body, a space is required to arrange a lever on a back lid side of this bridge member. This accordingly increases an outer dimension of the watch movement (mechanical assembly) and also a thickness of the movement.
(2) Because the pawl lever can be seen directly at the back lid, the oil supplied to a rotational part of the pawl lever and to the pawl is seen at the back lid. It is accordingly difficult to improve appearance on the movement of a watch made with a back-lid skeleton.
(3) Because the pawl lever is arranged between the closest bridge member to the back lid and the oscillating weight body, the structure supporting the pawl lever is complicated.
Therefore, it is an object of the present invention to provide, in order to solve the foregoing problems in the conventional art, a self-winding watch having a reduced size and thickness by arranging a pawl lever on a main plate side of a bridge member.
Another object of the invention is to provide a self-winding watch which has a good aesthetic appearance from a back lid side of a movement.
Furthermore, another object of the invention is to provide a self-winding watch which can support a pawl lever by a simple structure.
In order to-solve the above problem, the present invention is structured such that, in a self-winding watch structure to wind up a spiral spring in a barrel complete through a self-winding mechanism due to rotation of an oscillating weight, the self-winding watch comprises: a main plate structuring a base plate of a self-winding watch; a bridge member rotatably supporting at least one shaft part of a wheel train constituting the self-winding mechanism; at least one first transmission wheel to be rotated by rotation of the oscillating weight; a pawl lever to be elastically moved by rotation of the first transmission wheel; a second reduction wheel to be rotated by eccentric motion of the pawl lever; and a barrel complete including a spiral spring to be wound up by rotation of the second reduction wheel; wherein the lever at least one part thereof is arranged on a side of the main plate with respect to the bridge member. This bridge member is structured, for example, by a third wheel bridge rotatably supporting a third wheel. This bridge member may be a part constituting a self-winding wheel train, a transmission wheel bridge rotatably supporting the oscillating weight or a train wheel bridge rotatably supporting a wheel train including the barrel complete. It is preferred that the first transmission wheel is structured by a first transmission wheel and the second reduction wheel is by a second reduction wheel.
Meanwhile, in the self-winding watch of the invention, the bridge member is preferably structured to rotatably receive at least one of a wheel train, constituting a self-winding mechanism.
This structure can reduce the size and thickness of self-winding mechanism and support the pawl lever by a simple structure.
Furthermore, the present invention is structured such that, in a self-winding watch structure to wind up a spiral spring in a barrel complete due to rotation of an oscillating weight, a main plate and at least one bridge member are provided. The oscillation weight is rotatably supported by the bridge member. This self-winding watch has a first transmission intermediate wheel to be rotated by rotation of the oscillating weight and a first transmission wheel structured to be rotated by rotation of the first transmission intermediate wheel. This first transmission wheel has an eccentric shaft part provided in a closer position to the main plate than the bridge member. A pawl lever is structured to eccentrically move due to rotation of the eccentric shaft part of the first transmission wheel. The pawl lever has at least one part arranged on a side of the main plate with respect to the bridge member. A second reduction wheel has a ratchet gear to be rotated in one direction by a feed pawl of the pawl lever.
The self-winding watch of the invention has a ratchet wheel to be rotated in one direction by rotation of the second reduction wheel, and a barrel complete accommodating a spiral spring to be wound up by rotation of the ratchet wheel.
In the self-winding watch of the invention, the first transmission intermediate wheel at its gear part and the first transmission wheel at its gear part may be structured arranged between the oscillation weight and the bridge member.
This structure improves appearance of the movement on its back lid side.
Also, in the self-winding watch of the invention, the gear part of the-first transmission intermediate wheel may have at least one part arranged on the main plate side of the bridge member. Furthermore, the gear part of the first transmission wheel may have at least one part arranged on the main plate side of the bridge member.
This structure can rotatably support the first transmission intermediate wheel and the first transmission wheel with positiveness.